Initial commit without Iterator

csc/2019/2.LockFreeSet/ChausovAG/pom.xml

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+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <groupId>dxahtepb</groupId>
+    <artifactId>lock-free-set</artifactId>
+    <version>1.0-SNAPSHOT</version>
+
+    <properties>
+        <maven.compiler.source>1.8</maven.compiler.source>
+        <maven.compiler.target>1.8</maven.compiler.target>
+    </properties>
+
+    <repositories>
+        <repository>
+            <id>bintray--maven</id>
+            <name>bintray</name>
+            <url>https://dl.bintray.com/devexperts/Maven</url>
+        </repository>
+    </repositories>
+
+    <dependencies>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>4.12</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.devexperts.lincheck</groupId>
+            <artifactId>lincheck</artifactId>
+            <version>2.0</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+</project>

csc/2019/2.LockFreeSet/ChausovAG/src/main/java/ru/cscenter/dxahtepb/lockfreeset/LockFreeSet.java

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+package ru.cscenter.dxahtepb.lockfreeset;
+
+/**
+ * Lock-Free множество.
+ * @param <T> Тип ключей
+ */
+public interface LockFreeSet<T extends Comparable<T>> {
+  /**
+   * Добавить ключ к множеству
+   *
+   * Алгоритм должен быть как минимум lock-free
+   *
+   * @param value значение ключа
+   * @return false если value уже существует в множестве, true если элемент был добавлен
+   */
+  boolean add(T value);
+
+  /**
+   * Удалить ключ из множества
+   *
+   * Алгоритм должен быть как минимум lock-free
+   *
+   * @param value значение ключа
+   * @return false если ключ не был найден, true если ключ успешно удален
+   */
+  boolean remove(T value);
+
+  /**
+   * Проверка наличия ключа в множестве
+   *
+   * Алгоритм должен быть как минимум wait-free
+   *
+   * @param value значение ключа
+   * @return true если элемент содержится в множестве, иначе - false
+   */
+  boolean contains(T value);
+
+  /**
+   * Проверка множества на пустоту
+   *
+   * Алгоритм должен быть как минимум wait-free
+   *
+   * @return true если множество пусто, иначе - false
+   */
+  boolean isEmpty();
+
+  /**
+   * Возвращает lock-free итератор для множества
+   *
+   * Итератор должен базироваться на концепции снапшота, см.
+   * @see <a href="http://www.cs.technion.ac.il/~erez/Papers/iterators-disc13.pdf">Lock-Free Data-Structure Iterators</a>
+   *
+   * @return новый экземпляр итератор для множества
+   */
+  java.util.Iterator<T> iterator();
+}

csc/2019/2.LockFreeSet/ChausovAG/src/main/java/ru/cscenter/dxahtepb/lockfreeset/LockFreeSetImpl.java

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+package ru.cscenter.dxahtepb.lockfreeset;
+
+import java.util.concurrent.atomic.AtomicMarkableReference;
+
+public class LockFreeSetImpl<T extends Comparable<T>> implements LockFreeSet<T> {
+  private final Node head = new Node(null, null);
+
+  @Override
+  public boolean add(final T value) {
+    while (true) {
+      final Pair pair = find(value);
+      final Node prev = pair.prevNode;
+      final Node curr = pair.nextNode;
+
+      if (curr == null || curr.value.compareTo(value) != 0) {
+        final Node node = new Node(value, curr);
+        if (prev.next.compareAndSet(curr, node, false, false)) {
+          return true;
+        }
+      } else {
+        return false;
+      }
+    }
+  }
+
+  @Override
+  public boolean remove(final T value) {
+    while (true) {
+      final Pair pair = find(value);
+      final Node prev = pair.prevNode;
+      final Node curr = pair.nextNode;
+
+      if (curr == null || curr.value.compareTo(value) != 0) {
+        return false;
+      } else {
+        final Node succ = curr.next.getReference();
+        if (!curr.next.compareAndSet(succ, succ, false, true)) {
+          continue;
+        }
+        prev.next.compareAndSet(curr, succ, false, false);
+        return true;
+      }
+    }
+
+  }
+
+  @Override
+  public boolean contains(final T value) {
+    final boolean[] holder = new boolean[1];
+    Node curr = head.next.get(holder);
+    while (curr != null && curr.value.compareTo(value) < 0) {
+      curr = curr.next.get(holder);
+    }
+    final boolean isCurrMarked = holder[0];
+    return curr != null && curr.value.compareTo(value) == 0 && !isCurrMarked;
+  }
+
+  private Pair find(final T value) {
+    retry:
+    while (true) {
+      Node prev = head;
+      Node curr = prev.next.getReference();
+
+      while (true) {
+        if (curr == null) {
+          return new Pair(prev, null);
+        }
+
+        final boolean[] holder = new boolean[1];
+        final Node succ = curr.next.get(holder);
+        final boolean isCurrMarked = holder[0];
+
+        if (isCurrMarked && !prev.next.compareAndSet(curr, succ, false, false)) {
+          continue retry;
+        } else {
+          if (!isCurrMarked && value.compareTo(curr.value) <= 0) {
+            return new Pair(prev, curr);
+          }
+          prev = curr;
+          curr = succ;
+        }
+      }
+    }
+  }
+
+  @Override
+  public boolean isEmpty() {
+    return head.next.getReference() == null;
+  }
+
+  @Override
+  public java.util.Iterator<T> iterator() {
+    return null;
+  }
+
+  private class Node {
+    final T value;
+    final AtomicMarkableReference<Node> next;
+
+    Node(final T value, final Node next) {
+      this.value = value;
+      this.next = new AtomicMarkableReference<>(next, false);
+    }
+
+    @Override
+    public String toString() {
+      return "Node(" + (value != null ? value.toString() : "null") + ")";
+    }
+  }
+
+  private class Pair {
+    final Node prevNode;
+    final Node nextNode;
+
+    Pair(final Node prevNode, final Node nextNode) {
+      this.prevNode = prevNode;
+      this.nextNode = nextNode;
+    }
+
+    @Override
+    public String toString() {
+      return "Pair("
+              + (prevNode != null ? prevNode.toString() : "null")
+              + ", "
+              + (nextNode != null ? nextNode.toString() : "null")
+              + ")";
+    }
+  }
+}

csc/2019/2.LockFreeSet/ChausovAG/test/main/java/ru/cscenter/dxahtepb/lockfreeset/LockFreeSetImplLincheck.java

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+package ru.cscenter.dxahtepb.lockfreeset;
+
+import com.devexperts.dxlab.lincheck.LinChecker;
+import com.devexperts.dxlab.lincheck.annotations.Operation;
+import com.devexperts.dxlab.lincheck.annotations.Param;
+import com.devexperts.dxlab.lincheck.strategy.stress.StressCTest;
+import com.devexperts.dxlab.lincheck.strategy.stress.StressOptions;
+import com.devexperts.dxlab.lincheck.verifier.linearizability.LinearizabilityVerifier;
+import org.junit.Test;
+
+@StressCTest(threads = 12)
+public class LockFreeSetImplLincheck {
+
+  private LockFreeSetImpl<Integer> lockFreeSet = new LockFreeSetImpl<>();
+
+  @Operation
+  public boolean add(@Param(name = "x") Integer x) {
+    return lockFreeSet.add(x);
+  }
+
+  @Operation
+  public boolean remove(@Param(name = "x") Integer x) {
+    return lockFreeSet.remove(x);
+  }
+
+  @Operation
+  public boolean contains(@Param(name = "x") Integer x) {
+    return lockFreeSet.contains(x);
+  }
+
+  @Operation
+  public boolean isEmpty(@Param(name = "x") Integer x) {
+    return lockFreeSet.contains(x);
+  }
+
+  @Test
+  public void runTest() {
+    LinChecker.check(LockFreeSetImpl.class, new StressOptions()
+            .iterations(20000)
+            .threads(12)
+            .actorsPerThread(100)
+            .invocationsPerIteration(200)
+            .verifier(LinearizabilityVerifier.class));
+  }
+}

csc/2019/2.LockFreeSet/ChausovAG/test/main/java/ru/cscenter/dxahtepb/lockfreeset/LockFreeSetImplTest.java

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+package ru.cscenter.dxahtepb.lockfreeset;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+public class LockFreeSetImplTest {
+
+  @Test
+  public void testEmptyByDefault() {
+    LockFreeSetImpl<Integer> set = new LockFreeSetImpl<>();
+    assertTrue(set.isEmpty());
+  }
+
+  @Test
+  public void testBasicOperations() {
+    LockFreeSetImpl<Integer> set = new LockFreeSetImpl<>();
+
+    assertFalse(set.contains(1));
+
+    assertTrue(set.add(1));
+    assertTrue(set.add(2));
+    assertTrue(set.add(4));
+    assertTrue(set.add(3));
+    assertFalse(set.add(1));
+    assertFalse(set.add(3));
+
+    assertTrue(set.contains(1));
+    assertTrue(set.contains(2));
+    assertTrue(set.contains(3));
+    assertTrue(set.contains(4));
+
+    assertTrue(set.remove(1));
+    assertFalse(set.contains(1));
+
+    assertFalse(set.remove(20));
+
+    assertFalse(set.isEmpty());
+
+    assertTrue(set.remove(2));
+    assertTrue(set.remove(3));
+    assertTrue(set.remove(4));
+    assertTrue(set.isEmpty());
+  }
+}